In the preparation of mass mailings, for example, it is often desired to attach a card, such as a credit card or the like, to a carrier document so that the former can be peeled easily from the carrier document for use by a consumer. One method of making such an attachment uses a pressure-sensitive, thermoplastic adhesive. During the printing or collating process, a portion of the thermoplastic adhesive is metered onto the carrier document and the card pressed against this material. The equipment for this process includes a heating container for the thermoplastic adhesive and a metering pump that may be electrically actuated.
Thermoplastic adhesive can be difficult to work with. Its high melting temperature and adhesive properties present some risk of burn to untrained operators. The price of the equipment for dispensing the thermoplastic adhesive and positioning and placing the attachments makes such equipment impractical for low volume mailings.
The present invention provides a method and apparatus allowing thermoplastic pressure-sensitive adhesives to be used simply and safely by those who have low-volume requirements. In the present invention, pressure-sensitive thermoplastic adhesive is pre-metered onto a release strip which may be rolled into coil. The size and spacing of the metered dots of thermoplastic adhesive allows one dot to be exposed at a time across an anvil plate which may be used to press the dot against a card or the like. The carrier strip may be advanced between the pressing operation to bring a new dot into position.
The spacing of the dots along the strip provides simple methods of dispensing the dots including the use of a specially constructed cardboard dispenser box or the like or various automated metering systems and mechanisms to be described.
Specifically, the present invention provides a thermoplastic adhesive dispensing tape having a flexible carrier tape extending longitudinally and having a transverse width and having opposed first and second release surfaces. Thermoplastic adhesive dots are arrayed longitudinally along the first release surface so that the carrier tape may be curved about an axis to expose a single adhesive dot to an abutting planar surface.
Thus, it is one object of the invention to provide a simple means for dispensing thermal plastic adhesive dots without requiring the expense or hazard of molten thermoplastic adhesive.
The second release surface may adhere less strongly to the thermoplastic adhesive dot than does the first release surface.
Thus, it is another object of the invention to provide a thermoplastic adhesive dispensing tape that may be unwound from a coil with the thermoplastic dots being retained on the first release surface.
The invention includes a method of manufacturing the thermoplastic adhesive dispensing tape by unrolling the flexible carrier strip from a first reel to expose the first release surface and dispensing molten thermoplastic adhesive at periodic intervals on the unrolled carrier strip. The carrier strip is then rerolled to compress the dispensed molten thermoplastic adhesive into flat disks.
Thus, it is another object of the invention to provide for adhesive disks that approximate the size and area that would be provided by an automatic dispensing equipment directly on the surfaces to be adhered together. The action of adjacent coils of the carrier strip mimics that of a card or other planar surface pressing against a molten portion of thermoplastic adhesives.
The rerolling of the flexible carrier strip may be delayed until the thermoplastic adhesive has skinned over.
Thus, it is yet another object of the invention to ensure that the thermoplastic adhesive dots are retained by the first release surface which receives the thermoplastic adhesive in a molten state prior to it skinning over and therefore adheres to it more strongly.
The step of dispensing molten thermoplastic adhesive may simultaneously dispense at least two separate portions of thermoplastic adhesive at transversely separated locations. The method may include the further step of longitudinally slitting the flexible carrier strip between separate portions of the thermoplastic adhesive prior to rerolling the flexible carrier strip.
Thus, it is another object of the invention to provide for a high throughput manufacture of dots with a single dispensing unit without jeopardizing the cooling of the dots as is necessary to allow them to skin over.
The invention also includes a dispensing apparatus for the thermoplastic adhesive dispensing tape, including a reel support, for holding the thermoplastic adhesive dispensing tape in coiled configuration, and a guide for receiving the carrier tape after adhesive dots have been removed. An anvil surface is positioned between the reel and the guide to receive the thermoplastic adhesive dispensing tape as unreeled from the coil and deform the thermoplastic adhesive dispensing tape to expose a single adhesive dot to a planar surface.
Thus, it is another object of the invention to provide a rapid application technique for the thermoplastic adhesive dots on the tape of the present invention. The positioning of the dots so that a single dot may be exposed to a planar surface allows the dots to be readily applied to planar surfaces by a proper incrementing of the tape over a correctly sized anvil surface.
The foregoing and other objects and advantages of the invention will appear from the following description. In this description, reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration, a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference must be made therefore to the claims for interpreting the scope of the invention.